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By N K. DavT, A Coggan

The performance of in situ, shallow water covers in controlling acid generation was evaluated at four recently decommissioned pyritic uranium tailings sites at Elliot Lake, Ontario, Canada. The tailings are acid generating, having a pyrite content of approximately five to ten per cent and a very low to non-existent alkaline buffering capacity. Adverse market conditions led to the closure of all operating uranium mines in the early- to mid-1990s, followed by rehabilitation and decommissioning of mine and waste management facilities. In order to control acidic drainage, all new and active tailings areas at Denison, Quirke, Panel, Spanish-American and Stanleigh mine sites were re-engineered to provide in situ submersion of these tailings under shallow water covers. The tailings impoundment dams were upgraded and reinforced or in some cases reconstructed, to minimise seepages and provide a minimum 1 m depth of water cover. With the exception of Stanleigh mine, which was closed in 1996 and rehabilitated during the late-1990s, the water covered Tailings Management Areas (TMAs) at other sites have been in operation for a period of six to nine years. The surface water quality at these sites is maintained at near neutral pH conditions by periodic addition of lime slurry to the established water covers. Additional treatment of effluent is provided as required to meet the discharge water quality standards. The performance of the established water covers at the sites was evaluated by analysing the annual equivalent limestone consumption data. The results were compared with the performance of an older, decommissioned Nordic TMA, which was rehabilitated using revegetation techniques. The water covers at these sites are performing as designed and acid generation has been reduced to low levels. Based on the total amount of yearly equivalent limestone required to maintain water quality in the water cover and at the effluent treatment plant, it is concluded that acid generation rate at the Denison TMA has reduced to less than 0.15 per cent of its pre-water cover conditions during normal operation and rehabilitation periods. In comparison to the revegetated Nordic TMA, the acid generation rates at Denison and Panel TMAs have decreased to less than 1.6 per cent of that at the Nordic TMA. The acid generation rate at the Quirke TMA was comparable or only slightly lower than that at the Nordic TMA because of its unique terraced cell configuration, having tailings in five hydraulically interconnected cells at different elevations. Historic acidity and oxidation reaction products, accumulated during normal operating and pre-water cover periods, are flushing from upstream locations to downstream cells, thus requiring much higher equivalent limestone additions for acid neutralisation and effluent treatment.

Jan 1, 2003

By Giles D, Wegmann D

The Mt Todd Gold Project is located 42 km northwest of the township of Katherine within the Northern Territory of Australia. It is situated in the southeastern portion of the Pine Creek Geosyncline. The Batman gold deposit, the largest of several deposits at Mt Todd, hosts an identified mineral resource of 92.9 million tonnes (Mt) grading 1.4 grams/tonne (g/t) as at 31 December 1993. Host rocks at Batman are assigned to the Early Proterozoic Burrell Creek Formation, comprising greywacke and siltstone interbedded with shale. Gold mineralisation is associated with a very broad zone of sheeted and stockwork quartz-sulphide veins that occupy a corridor of intense brittle fracture and faulting. A conceptual model of formation involves the dilation of joints and micro-faults within overlying sediments during sinistral movement along a basement shear zone. Synchronous granite intrusion generated convective circulation of crustal fluids through the sedimentary pile resulting in the formation of auriferous quartz veins within favourable structures. The Batman zone of mineralisation is not directly related to fold structures which typify several other major gold deposits within the Pine Creek Geosyncline.

Jan 1, 1994

For too long we, as an industry, have borne the brunt of irrational claims, poor science and even worse, journalism with regards to our affect on the environment. To some of us, the overwhelming media attention on greenhouse warming, the polluting outputs of mineral processing or unthinkable depletion of natural resources has left us embarrassed and more unfortunately has turned bright young people away from a career in the minerals industry.This paper shows the hypocrisy associated with an element of the green movement and dispels some general myths on mining disseminated by radical environmentalists.The fallacy of the greenhouse warming effect will be scrutinised by common sense and the mining industryÆs use of land will be discussed and put in proper perspective.Problems associated with safety and emissions and the means to overcome such are discussed briefly.

Jan 1, 2004

By J Poniewierski, Varcos D

Efficient blasting requires constant vigilance with respect to the actual layout being used in the field. Objective measurement techniques are required in laying out a pattern as the 'by eye' or 'thumb suck' methods cannot guarantee consistent results in layout. Erratic blast results are the consequence of such an approach. In a case study at Sons of Gwalia mine, it was demonstrated that incorrect front burdens had a snowballing effect on otherwise carefully laid out blasts, resulting in both excessive amounts of boulders caused by preconditioning of bench fronts and tops, and tight digging. Both problems caused lower excavator productivity and excessive excavator damage, as well as making it difficult to set out subsequent blasts correctly. Several field measurement methods are available to aid in determining correct blast layouts and one is described in this paper.

Jan 1, 1994

By J Janus, J Krawczyk

Local accumulation of methane in workings of a longwall is one of the most common causes of mining accidents. This gas has many sources: it may leak from goaf through permeable sealings, or through gaps between roof support sections. This stream is then mixed with ventilation air. In the case of auxiliary ventilation ducts, or free jet fans, we have to consider the propagation of a clean air stream in areas with an air-methane mixture. Therefore, modelling the mixing process of methane with ventilation air is important for determining the hazardous areas and thus to ensure safety. Computational fluid dynamics (CFD), specifically the finite volume method, provides tools for such modelling. However, this method requires validation. For this purpose, we have compared measurements with simulations for selected test cases having sufficient similarity to the present problems. In typical methane explosion hazard areas, such as a longwall, it is difficult to make measurements sufficiently to confirm credibility of 3D CFD simulations. As a relevant alternative, an injector methane drainage station placed in an underground gallery has been selected. The stream of drained goaf methane is entrained by compressed air powered injectors and then mixed with ventilation air. Research in this area does not interfere with mining operations, it can be performed safely in a repeatable way. Flow within the site has many similarities to conditions in mine drifts of the longwall area. Comparative research of measuring the methane concentration distribution in the mine drift downstream injector station, with simulations of propagation of the methane stream, was carried out. For measuring the methane concentration distribution in the mine drift a multipoint measurement velocity system developed at the Strata Mechanics Research Institute was used. For the simulation a finite volume method for turbulent flow of gas mixtures was applied. Preliminary results of comparison are shown as graphs and tables.CITATION:Janus, J and Krawczyk, J, 2013. An analysis of the mixing of air and methane in the stream produced by the mine injector station - Presenting preliminary results of measurements and modelling, in Proceedings The Australian Mine Ventilation Conference , pp 49-56 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By F D. I Hodgson

Twenty-seven observation test pits were excavated at four different spoils dumps at three collieries in the Witbank Coalfield. The holes were dug into the upper three metres of the spoils to ascertain if any weathering profiles, variation with age or influence of topsoil covering could be gauged. Samples from these holes were also subjected to laboratory testing (ABA, humidity cells and mineralogy on several selected samples). The test pits showed that there was a good correlation between in situ paste pH-values and ABA results for samples taken from the pits. At all the collieries, no correlation between age of spoils and in situ acidity could conclusively be drawn. The depth of soil cover also appears to be a minor consideration in determining the eventual acidity of the spoil. In the pits where acidity was found, the weathering was evident when contrasted to areas still buffered. It is unclear if the weathering leads to the acidity or vice versa, as the soil covering appeared to be similar. The spoils proved to be extremely variable with regard to particle size and material on a micro and macro scale. Evidence from most of the holes suggested that there was enough water contained in the fine material in the spoils to support the initiation of acid generation. Conclusions from this investigation are that the mineralogy of the spoils is the most important factor in determining the eventual occurrence of acidic hotspots, and that prior characterisation and selective handling will provide the best management practice for these spoils.

Jan 1, 2003

By C M. Côte, S Worden, K Svobodova

Mines in Queensland are transitioning to the progressive rehabilitation and closure plan (PRCP) framework. Mine operators are required to select and justify appropriate and viable post-mining land uses (PMLUs) following consideration of the surrounding landscape, community views and the objectives of local and regional planning strategies. The new approach offers opportunities for considering innovative PMLU options and collaborative use of post-closure mine assets, such as infrastructure (power, road/rail, buildings), dams and residual voids. Consideration of regional planning strategies will require a shift in thinking as mine closure is regulated and planned on an individual site basis and selection of PMLUs are commonly considered from this perspective. Planning at regional rather than site-specific scale offers strategic advantages, including the ability to align PMLU selection with the regional context and stakeholder aspirations (which could foster sustainable outcomes); address cumulative environmental and socio-economic impacts; consider options that are only viable at scale (ie across larger geographic areas); establish more extensive and connected ecological habitat corridors; reinstate larger expanses of functional agricultural land; and optimise regional resources (Hattingh, Williams and Corder, 2019). This paper presents the findings from a multidisciplinary project that identified PMLU options within Queensland’s four mining regions: the North-west Minerals Province, North Queensland, Bowen Basin and Clarence-Moreton and Surat Basin (Figure 1). To enable spatial analysis at the appropriate scale and to accommodate geographic diversity, North Queensland was divided into three geographical ‘focus areas’ – Weipa, Charters Towers and Tablelands. Delineation of the areas captured most of the mines within the wider region as well as regional characteristics and features.

Aug 2, 2023

By L Alem

In the field of mineral extraction, complex technologies are being introduced in mines, operators/technicians rely on assistance from an expert (or more) in order to keep their machines functioning. Personnel with such expertise, however, are not always physically on-site. There is a growing need for innovative technological solutions to support effective delivery, just in time, of remote guidance between an offsite expert and an on-site maintenance operator. To meet this need, we have, as part of our Human System Integration project within the CSIRO’s Minerals Down Under (MDU), Transforming the Future Mine theme, explored the usefulness of a number of emerging technologies including: augmented reality, wearable systems and touch table interfaces. This paper presents ReMoTe, an augmented realty system for remote guiding using a touch table interface for the expert station and a combination of augmented reality and a wearable system at the operator end. In designing this system we were interested in exploring the extent to which it can increase the productivity and safety of maintenance personnel. This paper also presents Mobile ReMote, our recent development of a fully mobile remote guiding system. In Mobile ReMote, both the expert and the operator are using a near eye display and wearing a light computer in a back pack. The expert is able to guide the operator using his/her hands on the virtual display, while the operator is able to see the instructions on the rear eye display. Workers in the mining industry are highly mobile, a mobile expert and operator station will meet this need.

Nov 22, 2011

By S Logan, J Pu, J Milsom, G McDonald

Management of environmental issues is an integral part of the mine decommissioning process. In Queensland, miners must comply with environmental aspects of the Mineral Resources Act and Contaminated Land legislation. Successful decommissioning involves the integration of a final Plan of Operations, decommissioning report addressing the mineÆs commitments included in its Environmental Management Overview Strategy (EMOS), and Site Contamination Report for relinquishment of leases under the Contaminated Land Act (1991). Niugini MiningÆs Red Dome Mine is proceeding through the decommissioning process. This paper discusses the important environmental management issues including sampling programs, management of culturally significant areas, assessment of background concentrations of target analytes, the use of historical reviews and risk assessment techniques, the timing of works, and the remediation/management of large areas of impacted land. The importance of a clear communications plan between key stakeholders is also discussed.

Jan 1, 1998

By Mine F. J, Woods P. H

Waste waters from mine sites may be screened for all constituents of significance as a first step in establishing water quality criteria for protection of aquatic ecosystems. Inductively-coupled plasma mass spectrometry (ICP-MS) offers the capability to screen water samples and digest solutions for virtually all elements in the periodic table. This technique is therefore able to identify elements whose concentrations are elevated in waste waters and may be rarely present in background surface or ground waters. Such elements may be present in waters at only a few ¦g/L. ICP-MS has sufficient sensitivity to detect sub-¦g/L or even ng/L levels of many elements. Waste waters from most mining activities in the Northern Territory have been examined by ICP-MS. The concentration data provide the basis of a contaminant data base. The data can show specific tracers in the ore or mineral itself, subsequently found in waste water. An example is the presence of rhenium in uranium ore. Such trace elements may be present in soluble or insoluble chemical forms and are more useful as indicators when soluble and exemplifying conservative chemical behaviour. The approach described, based on ICP-MS screening of mine site waste waters, together with general physico-chemical variables, provides the most comprehensive means yet available of selecting variables for monitoring programs and ensures that key elements and/or their chemical species are not excluded from monitoring programs.

Jan 1, 1994

By Morris P. H

A trial embankment was constructed using coarse coal mine reject on a deposit of crusted coal mine tailings at New Hope Colliery, located in the Bundamba District of the West Moreton Coalfields in South East Queensland, Australia. The purpose of the trial embankment was to assess the load carrying capacity and settlement behaviour of the crusted tailings, including an assessment of strength gain in the tailings under the influence of the fill. Prior to construction of the trial embankment, a site investigation of the tailings deposit was carried out. This comprised vane shear strength testing, together with disturbed sampling and undisturbed block sampling for the purposes of laboratory testing. Following the site investigation, settlement plates and standpipes were installed at various depths and locations within the tailings in the vicinity of the proposed embankment. The instrumentation enabled the magnitudes and distributions of settlement and pore pressure within the tailings to be determined during and following construction of the embankment. The embankment was constructed using coarse reject in three equal lifts to a height of 3.0 m. The tailings sustained a maximum settlement under the weight of the fill of 290 mm, representing about 4.2 ii of the average initial thickness of the tailings and a loss of embankment height of about 9.7 %. By the end of the monitoring period the strength of the softer tailings underlying therust had roughly doubled under the influence of tha cmbarikment

Jan 1, 1990

By G Hancock, J Lowry, T Coulthard, W Erskine, M Saynor

An important part of planning for the rehabilitation of uranium mine sites is the ability to assess the geomorphic stability of the final landform, over time frames ranging from decades to millenia. Depending on the environmental conditions, erosion features such as gullies may incise into containment structures, potentially leading to the exposure and transport of encapsulated radioactive material. Further, erosion may lead to increased sediment loads and the transport of other mine-related contaminants off-site and into downstream waterways. While erosion may be monitored and assessed over the short term (years to decades), the longer-term behaviour (centuries to millennia) of such landscapes is not within any meaningful human management time frame. Landscape evolution models (LEMs) can provide information on soil erosion rates at decadal or centennial scales over large spatial scales, and evaluate the sensitivity of these processes to environmental changes. However, an important issue associated with the use of models is the ability to assess the reliability and accuracy of the model. In this paper, the CAESAR-Lisflood LEM is tested for its ability to predict soil erosion from a series of 30 m × 30 m experimental plots specifically constructed for this purpose on a trial rehabilitated landform at the Ranger Uranium Mine in the Northern Territory, Australia. Model predictions of bedload and suspended sediment loads from the erosion plots were compared with field measured observations collected over four wet seasons from the trial landform. Once calibrated for the specific site hydrological conditions, the predicted sediment yield – specifically, bedload – demonstrated an excellent correspondence with the field data. However, longer-term simulations of ten years identified an exhaustion effect in sediment yield from the landform. These latter results indicate that a weathering function needs to be incorporated into CAESAR-Lisflood to ensure confidence that the CAESAR-Lisflood LEM will be able to correctly predict the long-term evolution of a rehabilitated landform once it has been?constructed.CITATION:Lowry, J,?Saynor, M,?Erskine, W, Coulthard, T and Hancock, G, 2014. A multi-year assessment of landform evolution model predictions for a trial rehabilitated landform, in Proceedings Life-of-Mine 2014 , pp 67–80 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

In the late 1970's Western Mining Corporation, Exploration Division considered the purchase of a major multi-element spectrometer as an adjunct to our existing atomic absorption spectrophotometers. The analytical work proposed for the unit included barium, uranium and rare earth elements from Olympic Dam, uranium, sulphur, vanadium and strontium on Yeelirrie type deposits, major element and whole rock analysis, multi-element analysis of samples from the laterite, chromium and manganese exploration programmes and tin and arsenic analysis. These were all analyses that were not readily or easily performed by flame atomic absorption or were where we expected that a simultaneous multi-element instrument would be an advantage. Also the turnaround times for the commercial laboratories was considered unacceptably long for some determinations. Other factors, important when considering the spectrometer were the ability to ensure confidentiality of results and the ability to assign our own priorities and not to have to rely on commercial laboratories. The two techniques considered were X-ray Fluorescence Spectrometry and Inductively Coupled Plasma Optical Emission Spectrometry. The decision was made in favour of the ICP unit for several reasons. The ICP fitted in with our existing methodology, ie samples digested for atomic absorption or colorimetric techniques would also be suitable for ICP analysis and vice versa. The technique was suitable for water samples and for major element analyses and for rare earth elements. X-ray fluorescence spectrometers were installed at the Kambalda and Belmont laboratories and would be available to us for routine checking and for elements not suitable for ICP analysis. The final consideration was price. ICP was considerably cheaper than XRF.

Jan 1, 1987

By B Maybee, L Fava, D Millar

In the context of a case study for an underground gold mine, the value generated by a schedule optimisation tool (SOT) is assessed. SOT is a software tool for underground mine planning that maximises the net present value (NPV) of a development and production schedule. A baseline study measures the NPV of a schedule generated by SOT from a sequence prepared by the site mine planners. Operational resource constraints and precedence constraints are adhered to by the schedule and NPV is evaluated with a financial model including revenues, costs and discount rate, as specified by the mine planner.The case study has several facets in addition to the baselining component. Scenarios were conducted that examined the degree of constraint on operational resources, the projected gold price and unit costs. Life-of-mine schedules subject to optimisation using SOT allowed for equitable comparisons.Haulage was identified as a dominant constraint for the mine. It was one of six operational resources that were used to constrain the optimisation of the mine schedule, with alternative levels for some of these constraints being identified so that their effects on the NPV could be studied. Alternative price projections for gold and different cost projections were identified and their effects on the optimised schedule examined. Price and cost scenarios that brought additional economic material into the schedule at various times in the mine life were considered in comparison to a scenario that assumed no additional economic material would become available.This case study illustrated that the use of a schedule optimisation tool to optimise mine schedules provides mine planners with an ability to perform a wide variety of analyses in a relatively short period of time. Such tools thereby support strategic decision-making that can add significant value to an orebody.The case study demonstrates that by fixing the set of development and production activities to be carried out before optimising the life-of-mine schedule, the mine planners can inadvertently set up a situation where the NPV would be progressively eroded in the last several years of the mine life. This clearly illustrates the need for schedule optimisation to be integrated with life-of-mine planning.CITATION:Fava, L, Maybee, B and Millar, D, 2012. Decision support for an underground gold mining operation - A case study using the schedule optimisation tool, in Proceedings Project Evaluation 2012 , pp 41-48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By S Paciornik

The traditional trading of iron ores is based on chemical specifications and particle size distribution. However, recent characterisation studies, that bring additional information like mineralogical composition and microstructural (textural) aspects, have become important. They contribute to determination of the iron ores downstream beneficiation operations and subsequent steelmaking processing, allowing improvements on both new and existing processes. Despite progress in commercial scanning electron microscope/energy dispersive spectrometer (SEM/EDS) automatic instruments in the last decade, these systems are not capable of performing the identification and discrimination of major iron ore minerals (haematite and magnetite) and the consequent description of its microstructure. On the other hand, reflected light microscopy (RLM) can easily distinguish the iron oxides by their reflectancies, but it cannot discriminate quartz and epoxy resin, which present similar colour on images. The present work proposes an innovative method to perform a quantitative mineralogy characterisation of iron ore based on RLM-SEM co-site microscopy. This technique combines images obtained by RLM and SEM through an automatic registration procedure that accurately aligns the two kinds of images of each field. In fact, it creates multi-dimensional images, which are then analysed using image processing and pattern recognition techniques. The case study is an itabiritic iron ore from Quadrilßtero Ferrffero (Brazil) which contains mainly quartz, goethite, magnetite and haematite. The discrimination of phases that are not distinguishable with either RLM (epoxy resin and quartz) or SEM (haematite and magnetite) can be performed through this multimodal approach, allowing the subsequent mineralogical quantification. The mineralogical quantification computed by image analysis was consistent with independently obtained results based on the Rietveld technique.

Jan 1, 2008

By H Kundapen, B R. Bolton, H Davies

The Ok Tedi porphyry copper-gold mine is located in the Star Mountains of Western Province, Papua New Guinea. Open-cut mine commenced in 1984 and is due to cease around 2010. The mine produces a total of 88 Mt of waste annually including 58 Mt overburden and 30 Mt tailings, which are discharged directly in to the Ok Tedi River. Mine derived wastes are transported downstream and deposited within the river channel in a variety of bar forms. The prevailing hydrogeological conditions including, velocity, competency, capacity, gradient, grain size and specific gravity, control the deposition and segregation of these sediments. Periodic exposure of the reactive sulfides to oxygen during fluctuations in the river discharge may result in oxidation, localised acid generation and liberation of metals into solution. To evaluate the significance of this issue, Ok Tedi Mining Limited initiated an investigation of the sediments deposited in the upper Ok Tedi River as part of its overall ARD Management Program. The specific objectives were to: evaluate the acid-forming characteristics of identified high sulfide river deposited sediments; characterise geochemically the waters in contact with sulfide-bearing river deposited sediments; map and monitor exposure areas and oxidation depth of deposited potentially acid forming (PAF) sediments; determine the depositional processes controlling sulfide distribution; and assess lag period, oxidation and metal release rates for the sediments. This work included the analysis of sediment and water samples collected on a 50 + 50 metre grid at six gravel/sand bars. The sediment samples were analysed for total sulfur, ANC, NAG, total sulfur and total copper. Water samples were tested for general water quality parameters, sulfate and a suite of dissolved metals including; Al, Ca, Cd, Cu, Fe-sol, K, Mg, Mn, Na, S and Zn. This paper presents the results of these investigations with particular emphasis on the geochemistry of the river sediments and associated contact waters.

Jan 1, 2003

By M F. L Gibson

The issue of flyrock is very important in the operation of all mineral extraction sites that use blasting. Unlike the other environmental effects of blasting, ground vibrations and air overpressure, flyrock is (or should be) a rare event, with severe consequences which may include damage to property, injury or fatalities. These physical consequences are often matched by a loss in public confidence in the management of the operation, mistrust and bad press. In this work a deterministic analysis of flyrock was carried out using the equations of a particle in motion with drag. The solutions to these equations were used to reproduce the curves of Lundborg et al (1975) for the relationship between flyrock boulder size and maximum ejection distance. A probabilistic approach based on Monte Carlo simulation was built up with the analytical model using published data together with local case study material. A typical quarry blast situation was modelled and estimates of safe standoff distances were determined using risk assessment techniques.

Jan 1, 2001

During the century past geologists have discovered an extraordinary range of mineral resources. It is somewhat surprising, in view of their success, to look back and find that geologists have been concerned through the entire time about the adequacy of resources to meet future needs. They continue to express concern. The basis of their concerns seems to rest as much in social issue as in evaluations of geology.Demand for mineral resources is driven by population and by per capita consumption. Both have grown steadily over the past century, and both continue to rise. In 1890 the global population was about 1.7 billion, people. It has now exceeded 5 billion and the growth rate is such that by the year 2000, the global population will be between 6~ and 7 billion. Demographic projections suggest the global population will approach 12 billion before a steady state is reached dnrino the centiirv ahead

Jan 1, 1990

By Riley S. J

The basic aim of mine planning is to design mine layouts and schedules that achieve optimisation of operations, minimum cost and maximum resource recovery. Successful accomplishment of this aim is facilitated by timely and comprehensive rehabilitation planning commencing at the pre-feasibility stage and continuing until the end of mining. Incorporation of a final landfomt design for waste rock dumps in a mine plan requires a prediction of surface stability, which may be achieved through erosion modelling. Erosion prediction models can be placed in two broad categories: soil loss prediction models eg USLE and CREAMS, and geomorphic models such as SIBERIA. A waste rock dump landform design based on selected slope form and grade and drainage systems should be developed as part of planning. A digital terrain model (DTM) of the landfonn should then be produced which can be modelled for long-term erosional stability using pre-determined parameter values. If acceptable standards of stability are not achieved, the landform should be redesigned and remodelled until the desired result is obtained. The planning process incorporating models requires knowledge of spoil or waste rock properties and model parameter values. This information is site specific and can be obtained from drill cores or costeans at the pre-mining stage and from spoil or waste rock during the mining stage. Realistic model parameter values are critical in post-mining landfonn design and can be obtained by several methods, including rainfall simulation, monitoring, geochemical analyses and grain size analysis.

Jan 1, 1994

By H Jalalifar, N Aziz

In the ten years since the University of NSW proposed a pillar design methodology for bord and pillar operations, the Australian coal mining industry has changed substantially. What was primarily a bord and pillar design approach is now being applied to chain pillar design in longwall mines where the requirements are substantially different. The dimensions of chain pillars can impact on tailgate conditions (roof, rib and floor), seal performance, and surface subsidence. The status of chain pillar design practice in Australia is reviewed, with a focus on defining pillar strength, chain pillar loading, and assessing the performance of the roof/pillar/system. A new pillar strength equation is proposed for Australian coal that applies for all width/height ratios. An alternative analysis of probability of failure of chain pillars is presented.

Jan 1, 2005